This application claims priority of German Patent Application No. 100 21 723.0 filed May 4, 2000.
The invention involves a tool head that has the ability for radially adjusting the position of the cutting tool.
A tool head of this type is known, for example, from DE 42 18 466 and consists of a tool having a cutting edge and a tool-holding fixture into which the tool is put. Equipment for setting the radial position of the cutting edge with regard to the axis of rotation is supplied in this tool head. This equipment consists of a pressing power converter between the base portion of the tool head and a driven element. Elastic swivel elements in the form of a parallel spring are provided between these parts that have different extension characteristics. The adjustment movement initiated through the pressing power converter is converted into a movement of the tool here, which is rigidly connected to the driven element. The radial position of the cutting edge of the tool is adjusted via these swivel elements.
There is a major need for manufacturing cylinder jacket surfaces, in particular, as dimensionally precise as possible. An excursion of approximately 0.1 mm is required here for the pure tool correction. Furthermore, fairly small plunge cuts and back-offs should also be possible, for which an adjustment distance of 2 to 3 mm is needed, however. This adjustment range is hardly capable of being realized in a reproducible fashion, though, with the known tool heads.
The problem of further developing a tool head of this type in such a way that a simple possibility of adjusting the cutting edge in a radial direction is created that permits both fairly large adjustment amounts, as well as an adjustment lying away from the axis of rotation, is a basis of the invention.
This problem is solved by the invention described herein.
The knowledge that greater adjustment possibilities of the cutting edge, with greater precision and other constructive possibilities, result through the transfer of the adjustment process with regard to bearing systems arranged in an eccentric fashion to each other known from another area to a tool head is a basis for the invention. On top of that, tool heads have a simple structure because of this.
The invention involves a tool head 10, which can be rotated around an axis of rotation 24, with a tool-holding fixture 14, 16 for a tool 20 having a cutting edge 18 and with equipment 38, 40, 44 for adjustment of the radial position of the tool cutting edge 18 with regard to the axis of rotation 24. The invention distinguishes itself by the fact that the tool-holding fixture is divided up into a base element 14, which is supported in a first bearing system 40 in a carrier sleeve 44 so as to be able to rotate around the axis of rotation 24, and a tool-holding element 16, which is supported in a second bearing system 38 in the carrier sleeve 44 so as to be able to rotate around an eccentric axis 42 that is positioned in an eccentric fashion, as well as in parallel to, the axis of rotation 24. The carrier sleeve 44 can be rotated around the axis of rotation 24, the axis of rotation 24 and the eccentric axis 42 lie on a guide line 52, and the tool-holding element 16 and the base element 14 are coupled to each other through a radial guide 48, 50 so as to be secure against twisting and capable of moving along the guide line 52 in such a way that the distance between the tool-holding element 16 and the base element 14, and consequently between the axis of rotation 24 and the eccentric axis 42, change via movement of the carrier sleeve 44 around the axis of rotation 24.
In accordance with the invention, the tool-holding fixture of the tool head is divided up into a base element, which is supported in a first bearing system in a carrier sleeve so as to be capable of rotating around the axis of rotation, and into a tool-holding element, which is supported in a second bearing system in the carrier sleeve so as to be capable of rotating around an eccentric axis lying parallel and in an eccentric fashion to the axis of rotation. The carrier sleeve can be rotated around the axis of rotation here, the axis of rotation and the eccentric axis lie in a guide line, and the tool-holding element and the base element are coupled with each other in a manner that is secure against twisting and that permits motion along the guide line in such a way that the distance between the tool-holding element and the base element, and consequently between the axis of rotation and the eccentric axis, changes by moving the carrier sleeve around the axis of rotation.
Radial adjustment movements can be carried out because of this in a simple way, without axial changes in the position of the cutting edge coming about. The radial adjustment movements can also include fairly large adjustment distance according to this principle. The maximum distance between the eccentric axes corresponds in the process to half a revolution. If, for example, the maximum distance is 0.1 mm, then the adjustment possibility is 0.1 mm/360xc2x0. This results in high resolution with good precision adjustment.
By turning the carrier sleeve around an angle of 90xc2x0, the distance of the axis of rotation to the eccentric axis changes between 0 and the maximum, for example 3 mm.
In accordance with one design form of the invention, the carrier sleeve has been developed as a handle for manual turning around the axis of rotation. This makes quick manual adjustment possible; the carrier sleeve is scaled here, in order to note the rotation movement. Adjustment is only possible when the tool head is at a standstill here.
As an alternative or supplement to this, the carrier sleeve works together with a drive unit, in particular an electrical one. It is then possible because of this to carry out precision adjustments even during the circulation of the tool head.
As an example, the electrical drive unit includes a rotor disk that is located on the outside of the carrier sleeve, and a drive unit coil that is located above and below the rotor disk, that are each connected to the drilling head. The carrier sleeve can now be moved in one direction or another in a simple fashion through the rotor disk by exciting the drive unit coils, and the radial position of the tool-holding element and of the cutting edge can consequently be adjusted.
In accordance with one design form of the invention, a joint spring is provided between a first bearing system and the tool-holding fixture, and the second bearing system and the base element, in particular a parallel spring, that permits relative movement of the tool-holding fixture vis-a-vis the base element. Special forms of tool-holding fixtures and special construction designs for axially securing the tool-holding fixture can be used because of this. The spring serves as a transfer element of the adjustment movement to the tool-holding element in the process. The spring completely encompasses the tool-holding element and the base element in sections.
In accordance with one preferred design form of the invention, the spring has a first recess in the cross-section running in parallel to the axis of rotation, to which a second recess vertically extends. In particular, the second recess is open towards the inside.
An equalization disk is put into the second recess so that the spring can also transfer axial forces. The equalization disk is preferably coated and/or surface-treated for better sliding. It can also have roller guides, though.
In order to transfer forces from the spindle driving the tool head without a float and in order to avoid tolerance-related cutting edge maladjustment from coming about, the tool-holding element and the base element are braced together with each other in the axial direction in an adjustable way.
In accordance with one design form of the invention, the drive unit generates oscillating, angular movement. Non-circular bore holes can be created in a simple way because of this.
The drive unit for the carrier sleeve can also be designed so as to be mechanical; in particular it can include a friction wheel, a toothed rack or a ratchet wheel for the fine adjustment of the carrier sleeve.
The base element is preferably an integral part of the spindle.
Other benefits and features arise from the following description of three design forms of the invention in connection with the drawing.